1. Field of the Invention
The present invention relates to a technique for controlling the operation of a pump and pumping system; and more particularly, the present invention relates to a method and apparatus for controlling and/or monitoring a pump, e.g., including for domestic and commercial heating or cooling water systems.
2. Brief Description of Related Art
FIG. 1 shows schematically a conventional constant pumping hydronic heating system, where hot water supplied from a boiler by a primary pump is transferred to heating zones by a secondary pump and circulated through zones by circulators respectively. A three way valve controlled by a temperature sensor detours incoming water partially into heating zones to maintain the flow rate requested for the temperature setup at zones and bypasses the rest of the incoming water into bypass pipelines, respectively. Following this configuration, there is significant energy waste in the system, including the energy loss due to flow dynamic friction through the bypass pipelines and valves, as well as the water thermal energy loss in bypass lines.
Recently, variable speed pump controls with energy saving control means or techniques, such as a linear curve control or a quadratic curve control, were disclosed for hydronic pumping control applications. However, the amount of energy that might be saved by these energy saving control means or techniques is mostly dependent on the control parameters set up, for instance, system design values on pressure and flow rate which are unknown in general to an operator due to the complexity of a hydronic system in service. In addition, the flow rate in the system may vary from time to time depending on the temperature settings and weather conditions outside as well.
In view of this, there is a need in the industry for an energy saving control means or technique, e.g., which is not only adaptive to the system curve, but to the flow rate associated with as well, so that pumping energy may be saved optimally.